1. Field of the Invention
The present invention relates to a multi-ply fibrous web, and, more particularly to a multi-ply fibrous web with a reduced adhesion border.
2. Description of the Related Art
Several different former combinations have been proposed for the manufacturing of plasterboard:
In a machine design including two gap formers, drainage in both gap formers is affected firstly on the top wire side and subsequently on the bottom wire side, resulting in a higher fines content on the bottom wire side. A back liner top side, with a lower fines content, is couched together with the top liner bottom side, which has a higher fines content.
In a machine design including several cylinder mold formers, a concentration of fines is produced on the cylinder wire side. The top sides, which have a low fines content, are couched together with the wire sides which have a high fines content.
In a machine design having two machine wire webs for the top liner and the back liner, respectively, together with a so-called BelLiner gap former for middle layers, a concentration of fines on the top side is produced with the machine wire webs, and a concentration of fines on the bottom wire side is produced with the BelLiner gap former. The sides of high fines content of the top liner and a first middle layer are couched together and the side of low fines content of the first middle layer is couched with a low fines side of a second middle layer and/or the back liner.
In a machine design including a combination of several machine wire webs, a concentration of fines is produced on the top side during the machine wire drainage process. The top liner and the middle layers are couched together with their top sides of high fines content and the bottom facing wire sides of low fines content. The middle layer and the back liner are couched together with their top sides of high fines content facing each other.
In a machine design for the packaging industry having two gap formers, a so-called “DuoFormer Base” (PB10656) and a so-called “DuoFormer Top” (PB10449) with the same web running direction are provided in the sheet-forming process. In this case, the top wire side of low fines content is couched together with the bottom wire side of high fines content.
A disadvantage of the above machines lies in the fact that purposeful separation of the back liner and middle layer is not possible.